247 lines
6.5 KiB
C
247 lines
6.5 KiB
C
#ifndef _ASM_X86_MMU_CONTEXT_H
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#define _ASM_X86_MMU_CONTEXT_H
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#include <asm/desc.h>
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#include <linux/atomic.h>
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#include <linux/mm_types.h>
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#include <trace/events/tlb.h>
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#include <asm/pgalloc.h>
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#include <asm/tlbflush.h>
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#include <asm/paravirt.h>
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#include <asm/mpx.h>
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#ifndef CONFIG_PARAVIRT
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static inline void paravirt_activate_mm(struct mm_struct *prev,
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struct mm_struct *next)
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{
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}
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#endif /* !CONFIG_PARAVIRT */
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#ifdef CONFIG_PERF_EVENTS
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extern struct static_key rdpmc_always_available;
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static inline void load_mm_cr4(struct mm_struct *mm)
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{
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if (static_key_false(&rdpmc_always_available) ||
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atomic_read(&mm->context.perf_rdpmc_allowed))
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cr4_set_bits(X86_CR4_PCE);
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else
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cr4_clear_bits(X86_CR4_PCE);
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}
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#else
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static inline void load_mm_cr4(struct mm_struct *mm) {}
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#endif
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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/*
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* ldt_structs can be allocated, used, and freed, but they are never
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* modified while live.
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*/
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struct ldt_struct {
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/*
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* Xen requires page-aligned LDTs with special permissions. This is
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* needed to prevent us from installing evil descriptors such as
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* call gates. On native, we could merge the ldt_struct and LDT
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* allocations, but it's not worth trying to optimize.
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*/
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struct desc_struct *entries;
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int size;
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};
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/*
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* Used for LDT copy/destruction.
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*/
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int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
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void destroy_context(struct mm_struct *mm);
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#else /* CONFIG_MODIFY_LDT_SYSCALL */
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static inline int init_new_context(struct task_struct *tsk,
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struct mm_struct *mm)
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{
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return 0;
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}
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static inline void destroy_context(struct mm_struct *mm) {}
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#endif
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static inline void load_mm_ldt(struct mm_struct *mm)
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{
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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struct ldt_struct *ldt;
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/* lockless_dereference synchronizes with smp_store_release */
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ldt = lockless_dereference(mm->context.ldt);
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/*
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* Any change to mm->context.ldt is followed by an IPI to all
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* CPUs with the mm active. The LDT will not be freed until
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* after the IPI is handled by all such CPUs. This means that,
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* if the ldt_struct changes before we return, the values we see
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* will be safe, and the new values will be loaded before we run
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* any user code.
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*
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* NB: don't try to convert this to use RCU without extreme care.
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* We would still need IRQs off, because we don't want to change
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* the local LDT after an IPI loaded a newer value than the one
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* that we can see.
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*/
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if (unlikely(ldt))
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set_ldt(ldt->entries, ldt->size);
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else
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clear_LDT();
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#else
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clear_LDT();
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#endif
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DEBUG_LOCKS_WARN_ON(preemptible());
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}
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static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
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{
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#ifdef CONFIG_SMP
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if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
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this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
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#endif
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}
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static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
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struct task_struct *tsk)
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{
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unsigned cpu = smp_processor_id();
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if (likely(prev != next)) {
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#ifdef CONFIG_SMP
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this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
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this_cpu_write(cpu_tlbstate.active_mm, next);
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#endif
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cpumask_set_cpu(cpu, mm_cpumask(next));
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/* Re-load page tables */
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load_cr3(next->pgd);
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trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
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/* Stop flush ipis for the previous mm */
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cpumask_clear_cpu(cpu, mm_cpumask(prev));
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/* Load per-mm CR4 state */
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load_mm_cr4(next);
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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/*
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* Load the LDT, if the LDT is different.
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*
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* It's possible that prev->context.ldt doesn't match
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* the LDT register. This can happen if leave_mm(prev)
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* was called and then modify_ldt changed
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* prev->context.ldt but suppressed an IPI to this CPU.
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* In this case, prev->context.ldt != NULL, because we
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* never set context.ldt to NULL while the mm still
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* exists. That means that next->context.ldt !=
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* prev->context.ldt, because mms never share an LDT.
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*/
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if (unlikely(prev->context.ldt != next->context.ldt))
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load_mm_ldt(next);
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#endif
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}
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#ifdef CONFIG_SMP
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else {
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this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
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BUG_ON(this_cpu_read(cpu_tlbstate.active_mm) != next);
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if (!cpumask_test_cpu(cpu, mm_cpumask(next))) {
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/*
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* On established mms, the mm_cpumask is only changed
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* from irq context, from ptep_clear_flush() while in
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* lazy tlb mode, and here. Irqs are blocked during
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* schedule, protecting us from simultaneous changes.
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*/
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cpumask_set_cpu(cpu, mm_cpumask(next));
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/*
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* We were in lazy tlb mode and leave_mm disabled
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* tlb flush IPI delivery. We must reload CR3
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* to make sure to use no freed page tables.
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*/
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load_cr3(next->pgd);
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trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
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load_mm_cr4(next);
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load_mm_ldt(next);
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}
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}
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#endif
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}
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#define activate_mm(prev, next) \
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do { \
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paravirt_activate_mm((prev), (next)); \
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switch_mm((prev), (next), NULL); \
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} while (0);
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#ifdef CONFIG_X86_32
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#define deactivate_mm(tsk, mm) \
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do { \
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lazy_load_gs(0); \
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} while (0)
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#else
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#define deactivate_mm(tsk, mm) \
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do { \
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load_gs_index(0); \
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loadsegment(fs, 0); \
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} while (0)
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#endif
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static inline void arch_dup_mmap(struct mm_struct *oldmm,
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struct mm_struct *mm)
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{
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paravirt_arch_dup_mmap(oldmm, mm);
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}
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static inline void arch_exit_mmap(struct mm_struct *mm)
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{
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paravirt_arch_exit_mmap(mm);
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}
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#ifdef CONFIG_X86_64
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static inline bool is_64bit_mm(struct mm_struct *mm)
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{
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return !config_enabled(CONFIG_IA32_EMULATION) ||
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!(mm->context.ia32_compat == TIF_IA32);
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}
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#else
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static inline bool is_64bit_mm(struct mm_struct *mm)
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{
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return false;
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}
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#endif
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static inline void arch_bprm_mm_init(struct mm_struct *mm,
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struct vm_area_struct *vma)
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{
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mpx_mm_init(mm);
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}
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static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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/*
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* mpx_notify_unmap() goes and reads a rarely-hot
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* cacheline in the mm_struct. That can be expensive
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* enough to be seen in profiles.
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*
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* The mpx_notify_unmap() call and its contents have been
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* observed to affect munmap() performance on hardware
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* where MPX is not present.
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*
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* The unlikely() optimizes for the fast case: no MPX
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* in the CPU, or no MPX use in the process. Even if
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* we get this wrong (in the unlikely event that MPX
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* is widely enabled on some system) the overhead of
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* MPX itself (reading bounds tables) is expected to
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* overwhelm the overhead of getting this unlikely()
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* consistently wrong.
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*/
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if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
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mpx_notify_unmap(mm, vma, start, end);
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}
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#endif /* _ASM_X86_MMU_CONTEXT_H */
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